KOH KRED, THAILAND - Sixteen-year-old Kaew slumped into unconsciousness in a van somewhere in southern Thailand, believing she was on her way to work in a textile factory near the border. She woke up in Malaysia to discover that she had been sold into the sex trade.

Hers is just one of a multitude of cases of modern-day slavery in Thailand, most of which involve a mix of poverty, violence and betrayal.

Apparently drugged and later locked in a room in Kuala Lumpur, Kaew met three other Thai women who asked if she had been lured to work like them. "I had no idea what they were talking about, but then they told me what kind of job they did and what kind of job I had to do. I was very scared," said Kaew, whose name AFP has changed to protect her identity.

She managed to escape before her first job, using money she had been given to buy food to take a taxi to the Thai embassy. Now she is now being cared for at Baan Kredtrakarn, a government-run shelter just outside Bangkok. But she can't help thinking of the women she left behind - or her abductors. "I want them to be punished. I am very angry," she said.

The US State Department last month put Thailand on its human trafficking watchlist, accusing it of not doing enough to combat trafficking. It said the country was a source, destination and transit point for trafficking, with ethnic minorities and citizens of neighbouring countries at particular risk of sexual abuse or forced labour.

Victims - mainly from Myanmar, Cambodia and Laos - have been found in the fishing industry, seafood factories, sweatshops and domestic work, while young girls are also ensnared in Thailand's vast sex industry. They form part of a vast shadow economy across Asia that generates about 10 billion dollars in yearly profits from forced labourers, mainly prostitutes, according to a 2005 report by the International Labour Organisation (ILO).

It estimated there were 1.36 million trafficking-related victims in forced labour in the Asia-Pacific region - more than half the global total.

Thai authorities are believed to have identified and helped 530 foreign victims of trafficking last year and repatriated 79 Thai citizens who had been taken overseas. But experts say that is just the tip of the iceberg, partly because many victims do not want to identify themselves by making a complaint. "The fact is we just do not have an accurate understanding of the numbers for Thailand, but we do know that the problem is significant," said Allan Dow, an expert at the ILO.

Thailand has said the US report did not take into account its efforts to curb human trafficking. The country has introduced a scheme to register migrants to give them legitimacy, and reached agreements with its neighbours to cooperate on tackling the issue.

But experts said costly registration procedures, the risk of extortion by corrupt police or civil servants and - in Myanmar's case - fear of the authorities mean people often shy away from going through legal channels.

Phil Robertson, Human Rights Watch's deputy Asia director, said Thai officials needed to recognise that trafficking "will stain their record" internationally. "In the worse forms of exploitation that these migrant workers face, they are being trafficked into situations where they may be held for months or years with no pay and physical and sexual abuse," he said.

With porous borders and a prosperous economy compared to some of its neighbours, Thailand is a magnet for migration. The challenges faced by authorities are huge, particularly as trafficking networks are seldom more than loose connections.

Victims are often approached by acquaintances who promise lucrative work across the border. When there is no way back, they find they have been duped. That's what happened to Bopha, a 40-year-old Cambodian woman who arranged a job in a fish ball factory in Thailand through a broker. After more than a month working from 6:00 am until at least midnight she still had not been paid. "I cried every day but I had to hide it," she said.

Workers were imprisoned inside the factory compound by high walls, barbed wire and security cameras, and those who tried to escape were beaten. "When I saw them hit people I thought, we are all human why do they have to do this when we just came to work?" said Bopha, whose name AFP has also changed.

In the end one worker was able to use a smuggled mobile phone to call his relatives and arrange a rescue. Now at the same shelter as Kaew, she yearns to see her family again. "I am old. I think a lot,"